1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method for processing an image of a subject.
2. Description of the Related Art
An optical coherence tomography (OCT) technique using interference of multi-wavelength light enables acquisition of a high-resolution tomographic image of a sample (in particular, a fundus of the eye).
In recent years, an ophthalmologic OCT apparatus can acquire, in addition to a normal OCT image of a shape of a fundus tissue, a polarization-sensitive OCT image using a polarization parameter (i.e., retardation and orientation), which is an optical characteristic of the fundus tissue.
The polarization-sensitive OCT (PS-OCT) allows generation of the polarization-sensitive OCT image using the polarization parameter, and identification and segmentation of a fundus tissue. PS-OCT uses the fact that some layers in the retina (or fundus) of an eye reflect polarized light differently from other layers. International Publication No. WO 2010/122118 A1 discusses a polarization-sensitive OCT which employs, as a measuring beam for examining the sample, a light beam that has been modulated to a circularly-polarized beam. Detection is then performed by splitting the interference light into linearly-polarized beams perpendicular to each other, so that the polarization-sensitive OCT image is generated with different layers in the fundus being imaged differently depending on their interaction with the polarized light. However, International Publication No. WO 2010/122118 A1 does not discuss performing diagnosis support, i.e., the original objective of the polarization-sensitive OCT. More specifically, International Publication No. WO 2010/122118 A1 does not discuss a method for automatically detecting a retinal layer of the subject's eye from the polarization-sensitive OCT image. In general, there is a layer which can be more easily identified using the polarization-sensitive OCT image as compared to using the tomographic image acquired by employing a conventional OCT method.